Many apparatuses are used as an apparatus arranged to align an object on a stage in which the stage moves on a surface plate. Among such apparatuses, there exists an apparatus which has two beam-like moving members that can move in two directions perpendicular to each other and a stage that moves in accordance with the moving members, and in which these moving members are guided in the respective directions by guides to drive the stage. This type of apparatus has motors which drive a moving member at the two ends thereof, and the motors with an excellent driving capability can be arranged. Hence, a stage can be moved at high speed. Since the stage and the motors are separated from each other, the motors can efficiently be cooled. In this type of apparatus, however, the two moving members may thermally expand, each moving member and its motors may be different in parallelism, or the moving member may rotate in the horizontal direction. For this reason, the moving members and stage, which can inherently move relative to each other, are likely to excessively constrain each other. When the moving members and stage fall into this excessive constraint state, they may come in contact with each other to restrict mutual movement, or the alignment precision of the stage may degrade due to vibrations caused by interference between the two moving members.
In a method disclosed in Japanese Patent Laid-Open No. 9-34135, a mechanical means is provided, and the fit tolerance of the first moving member and stage is improved to tightly fit them with no play while the second moving member and stage are loosely fitted, thereby attempting to solve the above-mentioned problem.
In a conventional method, however, new vibrations may occur by providing a mechanism such as a spring or the like. Additionally, control of one of two moving members in a tight constraint state makes it difficult to align a stage at high precision. Moreover, the mechanism such as a spring or the like between the second moving member and a bearing increases the complexity of the apparatus.